U.S. patent application number 15/256851 was filed with the patent office on 2018-03-08 for image reading apparatus providing shading correction with foreign matter detection.
The applicant listed for this patent is KABUSHIKI KAISHA TOSHIBA, TOSHIBA TEC KABUSHIKI KAISHA. Invention is credited to Toshimitsu Ichiyanagi, Naoyuki Misaka.
Application Number | 20180069985 15/256851 |
Document ID | / |
Family ID | 61280957 |
Filed Date | 2018-03-08 |
United States Patent
Application |
20180069985 |
Kind Code |
A1 |
Misaka; Naoyuki ; et
al. |
March 8, 2018 |
Image Reading Apparatus Providing Shading Correction with Foreign
Matter Detection
Abstract
In accordance with an embodiment, an image reading apparatus
comprises a sensor configured to read an image in a main scanning
direction; a first reference plate; a second reference plate; and a
processor configured to determine a parameter for shifting shading
correction data on the basis of first reference data obtained
through reading on the first reference plate by the sensor and
second reference data obtained through reading on the second
reference plate by the sensor, set the shading correction data on
the basis of data obtained through the reading on the first
reference plate by the sensor, acquire image data at each reading
position in the sub-scanning direction by the sensor and carry out
shading correction on the image data on the basis of the shading
correction data shifted according to a shift amount at the each
reading position obtained from the parameter.
Inventors: |
Misaka; Naoyuki; (Mishima
Shizuoka, JP) ; Ichiyanagi; Toshimitsu; (Sunto
Shizuoka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOSHIBA
TOSHIBA TEC KABUSHIKI KAISHA |
Tokyo
Tokyo |
|
JP
JP |
|
|
Family ID: |
61280957 |
Appl. No.: |
15/256851 |
Filed: |
September 6, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04N 1/0289 20130101;
H04N 2201/0081 20130101; H04N 1/193 20130101; H04N 1/4097 20130101;
H04N 1/1026 20130101 |
International
Class: |
H04N 1/409 20060101
H04N001/409; H04N 1/193 20060101 H04N001/193; H04N 1/028 20060101
H04N001/028 |
Claims
1. An image reading apparatus, comprising: a sensor configured to
read an image in a main scanning direction; a first reference plate
positioned in the main scanning direction; a second reference plate
positioned in the main scanning direction at a position different
from the first reference plate in a sub-scanning direction
orthogonal to the main scanning direction; and a processor
configured to determine a parameter for shifting shading correction
data on the basis of first reference data obtained through reading
on the first reference plate by the sensor and second reference
data obtained through reading on the second reference plate by the
sensor, set the shading correction data on the basis of data
obtained through the reading on the first reference plate by the
sensor, acquire image data at each reading position in the
sub-scanning direction by the sensor, and carry out shading
correction on the image data on the basis of the shading correction
data shifted according to a shift amount at the each reading
position obtained from the parameter, wherein the processor
specifies a first foreign matter position from the first reference
data, specifies a second foreign matter position from the second
reference data, and determines the parameter on the basis of the
first foreign matter position in the second foreign matter
position.
2. (canceled)
3. The image reading apparatus according to claim 1, wherein the
processor determines a parameter for linearly combining the first
foreign matter position and the second foreign matter position as
the parameter.
4. The image reading apparatus according to claim 1, wherein the
processor determines a moving average on the shading correction
data to determine the shading correction on the image on the basis
of the shading correction data to which the moving average is
performed.
5. The image reading apparatus according to claim 4, wherein the
processor performs an enlargement of a width of the moving average
as the position of the image data is close to the second reference
plate.
6. The image reading apparatus according to claim 5, wherein the
processor sets a width identical to or larger than the shift amount
as the width of the moving average.
7. The image reading apparatus according to claim 1, wherein the
processor determines the moving average on the shading correction
data to determine out the shading correction on the image on the
basis of the shading correction data to which the moving average
performed.
8. The image reading apparatus according to claim 7, wherein the
processor performs an enlargement of the width of the moving
average as the position of the image data is close to the second
reference plate.
9. The image reading apparatus according to claim 3, wherein the
processor determines the moving average on the shading correction
data to determine the shading correction on the image on the basis
of the shading correction data to which the moving average is
performed.
10. An image reading method, comprising: determining a parameter
for shifting shading correction data on a basis of first reference
data obtained through reading on a first reference plate formed in
a main scanning direction by a sensor that reads an image in the
main scanning direction and second reference data obtained through
reading on a second reference plate formed in the main scanning
direction at a position different from the first reference plate in
a sub-scanning direction orthogonal to the main scanning direction
by the sensor; setting the shading correction data on the basis of
data obtained through the reading on the first reference plate by
the sensor; acquiring image data at each reading position in the
sub-scanning direction by the sensor; and carrying out shading
correction on the image data on the basis of the shading correction
data shifted according to a shift amount at the each reading
position obtained from the parameter, wherein the parameter
comprises a parameter for realizing linear deviation of a position
of foreign matter in the image data from the distance between a
foreign matter position of a white reference plate and a foreign
matter position of a distortion detection plate while a carriage
moves between the white reference plate and the distortion
detection plate.
11. (canceled)
12. The image reading method according to claim 10, wherein the
parameter comprises linearly combining a foreign matter position of
a white reference plate and a foreign matter position of a
distortion detection plate.
13. The image reading method according to claim 10, wherein the
shading correction data comprises shading correction data of a
white reference and shading correction data of a black reference.
Description
FIELD
[0001] Embodiments described herein relate generally to an image
reading apparatus and an image reading method.
BACKGROUND
[0002] An image reading apparatus such as a scanner enables a
carriage to move under a fixed document to read the document. In
the image reading apparatus which enables the carriage to move to
read the document, due to an effect of variation of an assembly,
there is a case in which an actual moving route of the carriage
deviates from an intended moving route.
[0003] Further, in a case in which there is a foreign matter on a
light ray from the carriage to a sensor, a dent is generated in a
gain due to the foreign matter, which is detected by the sensor. If
the actual moving route of the carriage deviates from the intended
moving route, there is a case in which a position of the dent
deviates together with movement of the carriage.
[0004] Thus, there is a problem that the image reading apparatus
does not properly carry out shading correction for correcting
defects caused by the foreign matter.
DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a diagram illustrating an example of a
cross-sectional view of an image reading apparatus according to an
embodiment;
[0006] FIG. 2 is a block diagram illustrating an example of the
configuration of the image reading apparatus according to the
embodiment;
[0007] FIG. 3 is a graph illustrating an example of a gain acquired
by a CCD sensor according to the embodiment; and
[0008] FIG. 4 is a flowchart illustrating an example of operations
of the image reading apparatus according to the embodiment.
DETAILED DESCRIPTION
[0009] In accordance with an embodiment, an image reading apparatus
comprises a sensor, a first reference plate, a second reference
plate and a processor. The sensor reads an image in a main scanning
direction. The first reference plate is formed in the main scanning
direction. The second reference plate is formed in the main
scanning direction at a position different from the first reference
plate in a sub-scanning direction orthogonal to the main scanning
direction. The processor determines a parameter for shifting
shading correction data on the basis of first reference data
obtained through reading on the first reference plate by the sensor
and second reference data obtained through reading on the second
reference plate by the sensor, sets the shading correction data on
the basis of data obtained through the reading on the first
reference plate by the sensor, acquires image data at each reading
position in the sub-scanning direction by the sensor and carries
out shading correction on the image data on the basis of the
shading correction data shifted according to a shift amount at the
each reading position obtained from the parameter.
[0010] Hereinafter, the embodiment is described with reference to
the accompanying drawings.
[0011] The image reading apparatus according to the embodiment
reads an image from a document arranged on a document table. The
image reading apparatus is equipped with a carriage for reading the
image in a main scanning direction. The image reading apparatus
enables the carriage to move in a sub-scanning direction orthogonal
to the main scanning direction to read the whole of the
document.
[0012] FIG. 1 illustrates a cross-sectional view of an image
reading apparatus 1.
[0013] As shown in FIG. 1, the image reading apparatus 1 is
equipped with a housing 10, a document cover 20, a white reference
plate 30, a document table glass 35, a distortion detection plate
40, a lens 56, a CCD sensor 57, a CCD sensor substrate 58, a
control substrate 59, a first carriage 71 and a second carriage 72.
The image reading apparatus 1 reads an image from a document 2.
[0014] The housing 10 constitutes contour of the image reading
apparatus 1.
[0015] The document cover 20 is formed on the housing 10 and covers
the document 2. For example, one fixed end of the document cover 20
is rotatably fixed on the housing 10. The document cover 20 exposes
the document 2 if the other end thereof is lifted up.
[0016] The white reference plate 30 (first reference plate) is a
colorful member assumed as white reference with respect to a read
image of the CCD sensor 57. For example, the white reference plate
30 is a white plate formed into a rectangular shape. The white
reference plate 30 is formed in the main scanning direction in
which the first carriage 71 reads an image. In other words, the
white reference plate 30 is formed in a direction orthogonal to
FIG. 1. Further, the white reference plate 30 is formed in the main
scanning direction more widely than the width of the image acquired
by the CCD sensor 57 in the main scanning direction.
[0017] The document table glass 35 is formed by a rectangular
glass. The document table glass 35 loads the document 2. The
document table glass 35 is formed with a larger size than the
maximum document which can be read by the image reading apparatus
1. The document table glass 35 is formed in such a way as to being
incorporated in the housing 10. In other words, the document table
glass 35 enables light between the document 2 and the first
carriage 71 to be transmitted.
[0018] The document table glass 35 is formed behind the white
reference plate 30 in the sub-scanning direction (A direction in
FIG. 1) in which the first carriage 71 moves. In other words, the
first carriage 71 passes through the document table glass 35 after
passing through the white reference plate 30.
[0019] The distortion detection plate 40 (second reference plate)
is formed into a rectangular shape. The distortion detection plate
40 is formed inside the document cover 20 (in other words, at the
side contacting with the document table glass 35). The distortion
detection plate 40 is formed in the document cover 20 in the main
scanning direction in which the first carriage 71 direction
acquires the image. In other words, the distortion detection plate
400 is formed in the direction orthogonal to FIG. 1. Further, the
distortion detection plate 40 is formed more widely in the main
scanning direction than the width of the image acquired by the CCD
sensor 57 in the main scanning direction.
[0020] The distortion detection plate 40 is, for example, a white
plate or a black plate. The color of the distortion detection plate
40 is not limited to a predetermined configuration.
[0021] The distortion detection plate 40 is formed behind the
document 2 in the sub-scanning direction (A direction in FIG. 1).
In other words, the first carriage 71 passes through the distortion
detection plate 40 after passing through the document 2. The
distortion detection plate 40 is formed in the main scanning
direction at a position different from the white reference plate 30
in the sub-scanning direction.
[0022] The distortion detection plate 40 may be formed on the
document table glass 35. The distortion detection plate 40 may be
formed under the document table glass 35. Further, the distortion
detection plate 40 may be formed behind the document table glass 35
in the sub-scanning direction in the housing 10.
[0023] The first carriage 71 acquires the image in the main
scanning direction orthogonal to FIG. 1 from the document 2. The
first carriage 71 acquires light in the main scanning direction and
reflects the acquired light to the second carriage 72. The first
carriage 71 formed in the housing 10 moves in the sub-scanning
direction (A direction) along the top surface of the housing 10.
The first carriage 71 is formed at a location at which the first
carriage 71 can read the light reflected from the white reference
plate 30, the document 2 and the distortion detection plate 40 when
passing through the white reference plate 30, the document 2 and
the distortion detection plate 40.
[0024] The first carriage 71 is composed of light source 51, a
reflector 52 and a first mirror 53.
[0025] The light source 51 emits light illuminating the white
reference plate 30, the document 2 and the distortion detection
plate 40. For example, the light source 51 is an LED or a
fluorescent lamp.
[0026] The reflector 52 assembles the light emitted by the light
source 51 to a predetermined area. The reflector 52 focuses the
light to an area at which the first carriage 71 acquires the image.
For example, the reflector 52 is formed in a predetermined R to
cover the light source 51. The inside of the reflector 52 reflects
the light.
[0027] The first mirror 53 reflects the light from the
predetermined area to the second carriage 72 at a predetermined
angle. The first mirror 53 is formed in the first carriage 71 at a
predetermined angle. The first mirror 53 reflects the light in a
direction reverse to the A direction.
[0028] Necessary components may be properly added to the first
carriage 71 or unnecessary components may be properly deleted from
the first carriage 71.
[0029] The second carriage 72 reflects the light from the first
carriage 71 to the lens 56.
[0030] The second carriage 72 is equipped with a second mirror 54
and a third mirror 55.
[0031] The second mirror 54 reflects the light from the first
carriage 71 to the third mirror 55. The second mirror 54 is
arranged at a height almost identical to the first mirror 53. The
second mirror 54 reflects the light from the first mirror 53
downwards.
[0032] The third mirror 55 reflects the light from the second
mirror 54 to the lens 56. The third mirror 55 is formed almost
right under the second mirror 54. The third mirror 55 reflects the
light from the second mirror 54 in a direction almost parallel to
the A direction.
[0033] Necessary components may be properly added to the second
carriage 72 or unnecessary components may be properly deleted from
the second carriage 72.
[0034] The lens 56 forms an image with the light from the second
carriage 72 on the CCD sensor 57. The lens 56 is arranged at a
position almost horizontal to the third mirror 55. The lens 56
forms an image with the light from the third mirror 55 on the CCD
sensor 57.
[0035] The CCD sensor 57 converts the light from the lens 56 to an
electrical signal. For example, the CCD sensor 57 is composed of a
plurality of photoelectric conversion elements corresponding to
every read image pixel in the main scanning direction. Each
photoelectric conversion element of the CCD sensor 57 generates a
signal corresponding to intensity of light and sends the generated
signal to the CCD sensor substrate 58.
[0036] The CCD sensor substrate 58 controls the CCD sensor 57
according to a signal from the control substrate 59. The CCD sensor
substrate 58 is described later.
[0037] The control substrate 59 controls the whole of the image
reading apparatus 1. The control substrate 59 is described
later.
[0038] Next, a control system of the image reading apparatus 1 is
described.
[0039] FIG. 2 is a block diagram illustrating the control system of
the image reading apparatus 1.
[0040] As shown in FIG. 2, the image reading apparatus 1 is
equipped with the light source 51, the CCD sensor 57, the CCD
sensor substrate 58, the control substrate 59, a light source
control circuit 60, a drive system control circuit 61 and a motor
62.
[0041] The control substrate 59 is equipped with a processing IC
101, an image processing circuit 102, a timing generation circuit
103, an analog processing circuit 104 and a line memory circuit
105. The processing IC 101 is connected with the light source
control circuit 60, the drive system control circuit 61, the image
processing circuit 102, the timing generation circuit 103, the
analog processing circuit 104 and the line memory circuit 105 via a
data bus and an address bus.
[0042] The light source control circuit 60 controls the light
source 51 on the basis of the signal from the control substrate 59.
For example, the light source control circuit 60 controls electric
power supplied to the light source 51 on the basis of the signal
from the control substrate 59.
[0043] The drive system control circuit 61 controls a drive system
such as the motor 62 on the basis of the signal from the control
substrate 59. For example, the drive system control circuit 61
supplies electric power or a pulse to the drive system such as the
motor 62 on the basis of the signal from the control substrate
59.
[0044] The motor 62 enables the first carriage 71 to move on the
basis of the electric power or the pulse from the drive system
control circuit 61. The motor 62 is connected with the first
carriage 71 via a gear or a belt to enable the first carriage 71 to
move.
[0045] The processing IC 101 has functions of controlling
operations of the whole of the control substrate 59. The processing
IC 101 may be equipped with an inner cache and various interfaces.
The processing IC 101 executes various processing by executing a
program pre-stored in a memory which is not shown. The processing
IC 101 is, for example, a processor or may be a CPU.
[0046] A part of various functions realized in such a manner that
the processing IC 101 executes the program may be realized through
a hardware circuit. In this case, the processing IC 101 controls
the functions realized through the hardware circuit.
[0047] The image processing circuit 102 processes the image
acquired by the CCD sensor 57. For example, the image processing
circuit 102 sends the image acquired from the processing IC 101 to
an external configuration.
[0048] The timing generation circuit 103 generates various kinds of
timing. For example, the timing generation circuit 103 generates a
timing at which the CCD sensor 57 starts acquisition of an image or
a timing at which the CCD sensor 57 ends the acquisition of the
image on the basis of a signal from the processing IC 101. The
timing generation circuit 103 may output a pulse to notify a timing
to the external configuration.
[0049] The analog processing circuit 104 processes an analog signal
from the CCD sensor 57. For example, the analog processing circuit
104 converts the analog signal from the CCD sensor 57 to a digital
signal and sends the digital signal to the image processing circuit
102.
[0050] The line memory circuit 105 stores a parameter on the basis
of the signal from the processing IC 101. The parameter is
described later.
[0051] The CCD sensor substrate 58 is equipped with a CCD sensor
control circuit 201 and a CCD driver 202.
[0052] The CCD sensor control circuit 201 controls a timing of
driving the CCD sensor 57 according to the signal from the timing
generation circuit 103.
[0053] The CCD driver 202 drives the CCD sensor 57 on the basis the
signal from the CCD sensor control circuit 201. For example, the
CCD driver 202 supplies the electric power to the CCD sensor 57 on
the basis of the signal from the CCD sensor control circuit
201,
[0054] Necessary components may be properly added to the image
reading apparatus 1 or unnecessary components may be properly
deleted from the image reading apparatus 1.
[0055] Next, the functions realized by the processing IC 101 are
described.
[0056] Firstly, the processing IC 101 has a function of reading the
white reference plate 30 through the CCD sensor 57 to acquire white
reference data (first reference data).
[0057] For example, the processing IC 101 controls the motor 62
through the drive system control circuit 61 to enable the first
carriage 71 to move to a position at which the white reference
plate 30 can be read. The processing IC 101 reads the white
reference plate 30 through the CCD sensor 57 to acquire image data
of the white reference plate 30 as the white reference data. In
other words, the processing IC 101 acquires a position gain of each
position in the main scanning direction as the white reference
data.
[0058] Further, the processing IC 101 has a function of specifying
a position of a foreign matter (first foreign matter position) on
the basis of the white reference data. In other words, the
processing IC 101 specifies a position of a foreign matter adhering
to any position between the white reference plate 30 and the CCD
sensor 57 in the main scanning direction of the white reference
data.
[0059] For example, the processing IC 101 specifies a position into
which a value of a gain of the white reference data falls as the
position of the foreign matter. For example, the processing IC 101
averages the values of the gain of the white reference data. The
processing IC 101 specifies the position into which the gain falls
by a predetermined value or a predetermined rate according to the
average value as the position of the foreign matter.
[0060] Further, the processing IC 101 has a function of reading the
distortion detection plate 40 through the CCD sensor 57 to acquire
distortion detection data (second, reference data).
[0061] For example, the processing IC 101 controls the motor 62
through the drive system control circuit 61 to enable the first
carriage 71 to move to a position at which the distortion detection
plate 40 can be read. The processing IC 101 reads the distortion
detection plate 40 through the CCD sensor 57 to acquire image data
of the distortion detection plate 40 as the distortion detection
data. In other words, the processing IC 101 acquires a position
gain of each position in the main scanning direction as the
distortion detection data.
[0062] Further, the processing IC 101 has a function of specifying
a position of a foreign matter (second foreign matter position) on
the basis of the distortion detection data. In other words, the
processing IC 101 specifies a position of a foreign matter adhering
to any position between the distortion detection plate 40 and the
CCD sensor 57 in the main scanning direction of the distortion
detection data. The method of specifying the foreign matter
position of the distortion detection plate by the processing IC 101
is the same as the method of specifying the foreign matter position
of the white reference plate by the processing IC 101.
[0063] Further, the processing IC 101 has a function of determining
a parameter for shifting shading correction data used in shading
correction on the basis of the foreign matter position of the white
reference plate 30 and the foreign matter position of the
distortion detection plate 40. In other words, the processing IC
101 determines a parameter for shifting shading correction data in
accordance with deviation of the position of the foreign
matter.
[0064] For example, the processing IC 101 calculates a distance
between the foreign matter position of the white reference plate 30
and the foreign matter position of the distortion detection plate
40. The processing IC 101 determines a parameter as the parameter
for realizing linear deviation of position of the foreign matter in
the image data from the distance while the first carriage 71 moves
between the white reference plate 30 and the distortion detection
plate 40. In other words, the processing IC 101 determines a
parameter for linearly combining the foreign matter position of the
white reference plate 30 and the foreign matter position of the
distortion detection plate 40.
[0065] For example, if the distance between the white reference
plate 30 and the distortion detection plate 40 is set as L, the
foreign matter position of the white reference plate 30 is set as
WP, the foreign matter position of the distortion detection plate
40 set as DP, and a width (shift amount) of shifting the shading
correction data is set as S, D is represented by the following
equation.
S=(DP-WP)/L.times.x (1)
[0066] Herein, the position of the white reference plate 30 is
assumed as 0, and the position of the first carriage 71 is assumed
as x.
[0067] For example, the processing IC 101 calculates (DP-WP)/L as
the parameter.
[0068] Furthermore, the method of determining the parameter by the
processing IC 101 is not limited to a specify method.
[0069] The processing IC 101 stores the parameter in the line
memory circuit 105.
[0070] Further, the processing IC 101 has a function of setting the
shading correction data used in the shading correction.
[0071] The shading correction data is reference data to carry out
the shading correction. The shading correction data includes
shading correction data of white reference and shading correction
data of black reference.
[0072] The shading correction data of black reference is data
obtained by reading the predetermined area through the CCD sensor
57 in a state in which the light source 51 is turned off. For
example, the processing IC 101 controls the light source control
circuit 60 to turn off the light source 51. The processing IC 101
reads the image through the first carriage 71 located at the
predetermined position (for example, at the position of the white
reference plate 30) to acquire the image data in a state in which
the light source 51 is turned off. The processing IC 101 generates
the shading correction data of black reference on the basis of the
read image data in a state in which the light source 51 is turned
off.
[0073] Similarly, the shading correction data of white reference is
generated on the basis of the white reference data.
[0074] The processing IC 101 has a function of reading the document
2 through the first carriage 71. In other words, the processing IC
101 acquires the image data from the CCD sensor 57.
[0075] For example, the processing IC 101 controls the motor 62
through the drive system control circuit 61 to enable the first
carriage 71 to move towards the A direction. The processing IC 101
acquires the image data obtained by reading the document 2 through
the first carriage 71 if the first carriage 71 moves to the
predetermined position.
[0076] The processing IC 101 enables the first carriage 71 to move
to acquire the image data at a predetermined interval.
[0077] Further, the processing IC 101 has a function of calculating
a shift amount corresponding to a reading position on the basis of
the parameter.
[0078] For example, the processing IC 101 calculates a shift amount
corresponding to a reading position of the first carriage 71 on the
basis of the parameter stored in the line memory circuit 105. For
example, the processing IC 101 substitutes the reading position of
the first carriage 71 in the equation (1) to calculate the shift
amount.
[0079] Further, the processing IC 101 has a function of carrying
out the shading correction on the image data on the basis of the
shading correction data shifted according to the shift amount.
[0080] The processing IC 101 shifts the shading correction data
according to the calculated shift amount. The processing IC 101
calculates a moving average of the shifted shading correction data.
For example, the processing IC 101 enlarges the width of the moving
average as the first carriage 71 advances in the A direction. In
other words, the processing IC 101 reduces the width of the moving
average in a case in which the first carriage 71 is close to the
white reference plate 30. Further, the processing IC 101 enlarges
the width of the moving average as the first carriage 71 approaches
the distortion detection plate 40. For example, the processing IC
101 may set a width identical to or larger than the shift amount as
the width of the moving average.
[0081] The processing IC 101 may set the width of the moving
average to "1" (in other words, no moving average) in a case in
which the first carriage 71 is close to the white reference plate
30.
[0082] The processing IC 101 carries out the shading correction on
the image data on the basis of the shading correction data to which
the moving average is carried out. The shading correction corrects
uneven brightness generated due to characteristics of an optical
system to acquire image data with the same brightness. For example,
the processing IC 101 carries out the shading correction according
to the following equation.
Corrected image data=(image data-shading correction data of black
reference to which the moving average is carried out)/(shading
correction data of white reference to which the moving average is
carried out shading correction data of black reference to which the
moving average is carried out) (2)
[0083] Next, examples of the white reference data and the
distortion detection data are described.
[0084] FIG. 3 is a graph illustrating the examples of the white
reference data and the distortion detection data.
[0085] The vertical axis of FIG. 3 indicates the gain. The
horizontal axis of FIG. 3 indicates the position in the main
scanning direction in which the image is acquired.
[0086] A graph 301 indicates the white reference data. The graph
301 includes a point 302 on the mountainside. The point 302 is the
point into which the gain falls. In other words, the point 302 is
the position of the foreign matter such as rubbish in the white
reference data.
[0087] A graph 401 indicates the distortion detection data. The
graph 401 includes a point 402 on the mountainside. The point 402
is the point into which the gain falls. In other words, the point
402 is the position of the foreign matter such as rubbish in the
distortion detection data.
[0088] Next, an example of operations of the processing IC 101 is
described.
[0089] FIG. 4 is a flowchart illustrating the example of the
operations of the processing IC 101.
[0090] Herein, a power supply of the image reading apparatus 1 is
switched from off state to on state.
[0091] Firstly, the processing IC 101 carries out an initial
operation (ACT S11). For example, the processing IC 101 carries out
energization to each section of the image reading apparatus 1 or an
operation check of each section as the initial operation.
[0092] If the initial operation is carried out, the processing IC
101 reads the white reference plate 30 to acquire the white
reference data (ACT S12). If the white reference data is acquired,
the processing IC 101 reads the distortion detection plate 40 to
acquire the distortion detection data (ACT S13).
[0093] If the distortion detection data is acquired, the processing
IC 101 determines the parameter for shifting the shading correction
data of the shading correction on the basis of the white reference
data and the distortion detection data (ACT S14).
[0094] If the parameter is determined, the processing IC 101
determines whether or not scanning is started (ACT S15). For
example, the processing IC 101 determines whether to receive the
operation of starting the scanning through an operation
section.
[0095] If it is determined that the scanning is not started (NO in
ACT S15), the processing IC 101 returns to the processing in ACT
S15.
[0096] If it is determined that the scanning is started (YES in ACT
S15), the processing IC 101 reads the predetermined area after the
light source 51 is turned off to acquire the shading correction
data of black reference as the shading correction data (ACT
S16).
[0097] If the shading correction data of black reference is
acquired, the processing IC 101 reads the white reference plate 30
after the light source 51 is turned on to acquire the shading
correction data of white reference as the shading correction data
(ACT S17). If the shading correction data of white reference is
acquired, the processing IC 101 acquires the image data (ACT
S18).
[0098] If the image data is acquired, the processing IC 101
calculates the shift amount on the basis of the parameter (ACT
S19). If the shift amount is calculated, the processing IC 101
carries out the shading correction on the image data on the basis
of the shading correction data shifted according to the shift
amount (ACT S20). If the shading correction is carried out on the
image data, the processing IC 101 sends the image data after the
shading correction to another configuration through the image
processing circuit 102 (ACT S21).
[0099] If the image data after the shading correction is sent to
another configuration, the processing IC 101 determines whether or
not the reading of the image data is ended (ACT S22). For example,
the processing IC 101 determines whether or not the first carriage
71 moves to a predetermined end position.
[0100] If it is determined that the reading of the image data is
not ended (NO in ACT S22), the processing IC 101 returns to the
processing in ACT S18. For example, the processing IC 101 returns
to the processing in ACT S18 after standby for a time for which the
first carriage 71 moves at a predetermined distance.
[0101] If it is determined that the reading of the image data is
ended (YES in ACT S22), the processing IC 101 reads the distortion
detection plate 40 to acquire the distortion detection data (ACT
S23). For example, the processing IC 101 enables the first carriage
71 to continuously move towards the A direction to read the
distortion detection plate 40 after the reading on the document 2
is ended.
[0102] If the distortion detection data is acquired, the processing
IC 101 updates the parameter on the basis of the shading correction
data of white reference acquired in the processing in ACT S17 and
the distortion detection data acquired in the processing in ACT S22
(ACT S24). For example, the processing IC 101 uses the shading
correction data of white reference acquired in the processing in
ACT S17 as the white reference data. The processing IC 101
determines the parameter on the basis of the white reference data
acquired in the processing in ACT S17 and the distortion detection
data acquired in the processing in ACT S22 to store the determined
parameter in the line memory circuit 105.
[0103] If the parameter is updated, the processing IC 101 returns
to the processing in ACT S15.
[0104] Furthermore, the processing IC 101 may not carry out the
processing in ACT S23 and ACT S24. In other words, the processing
IC 101 executes the processing from ACT S12 to ACT S14 at the time
the power supply is turned on and may not update the parameter in
operation.
[0105] The processing IC 101 may execute the processing from ACT
S12 to ACT S14 at a predetermined interval. Further, the processing
IC 101 may execute the processing from ACT S12 to ACT S14 in a case
of receiving a predetermined operation through the operation
section.
[0106] The image reading apparatus 1 is equipped with the carriage
including an optical sensor formed in the main scanning direction
and may be equipped with a device for enabling the carriage to move
in the sub-scanning direction.
[0107] The image reading apparatus constituted as stated above
reads the white reference plate to acquire the white reference data
and reads the distortion detection plate to acquire the distortion
detection data. The image reading apparatus determines the
parameter for correcting distortion generated between the white
reference plate and the distortion detection plate on the basis of
the white reference data and the distortion detection data.
[0108] The image reading apparatus calculates the shift amount
corresponding to the position of the first carriage on the basis of
the parameter. The image reading apparatus shifts the shading
correction data according to the shift amount to carry out the
shading correction on the image data. As a result, the image
reading apparatus can properly carry out the shading correction
even if the concave position of the gain due to the distortion of
the housing changes depending on the position of the first
carriage.
[0109] Further, the image reading apparatus expands the width of
the moving average carried out on the shading correction data as
the first carriage advances to the terminal. As the first carriage
advances, there is a case in which the deviation between the
concave position of the gain of the image data and the position at
which the shading correction corrects the dent becomes large. In
such a case, the image reading apparatus can gradually carry out
the correction of the dent with the shading correction. As a
result, the image reading apparatus can reduce generated defects of
the image data with the shading correction.
[0110] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the invention. Indeed, the novel
embodiments described herein may be embodied in a variety of other
forms; furthermore, various omissions, substitutions and changes in
the form of the embodiments described herein may be made without
departing from the spirit of the invention. The accompanying claims
and their equivalents are intended to cover such forms or
modifications as would fall within the scope and spirit of the
invention.
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